Nutritional formulas today are well known for a variety of nutritional or disease specific applications in infants, children and adults. These formulas most typically contain a balance of proteins, carbohydrates, lipids, vitamins, and minerals tailored to the nutritional needs of the intended user, and include product forms such as ready-to-drink liquids, reconstitutable powders, nutritional bars, and others.
Among the many nutritional formulas commercially available today, infant formulas have become particularly well known and commonly used in providing a supplemental or sole source of nutrition early in life. Although human milk is generally accepted as a superior nutritional source for most if not all infants, many infant nutritional formulas can still provide a quality alternative for those mothers who cannot breastfeed or choose not to under their particular circumstances. These infant formulas typically contain proteins, carbohydrates, lipids, vitamins, minerals, and other nutrients, and are commercially and most typically available as reconstitutable powders, ready-to-feed liquids, and dilutable liquid concentrates.
Many nutritional formulas, especially infant formulas, commonly contain a variety of polyunsaturated chain fatty acids (PUFA) as part of the lipid component of the overall nutrient system, examples of which include linoleic acid, alpha-linolenic acid, eicosapentaenoic acid (EPA), arachidonic acid (ARA), decosahexaenoic acid (DHA), and others. A growing body of evidence even suggests the intake of certain long chain polyunsaturated fatty acids may be beneficial or even essential for certain groups. For example, some PUFAs have been shown beneficial in the prevention and management of cardiovascular disease, rheumatoid arthritis, asthma, other inflammation related diseases, and cancer cachexia.
Arachidonic and decosahexaenoic acids in particular have been shown to provide beneficial effects in preterm infants such as enhanced brain and vision development, and are now commonly found in many commercially available infant formulas such as Similac® Advance® Infant Formula and Isomil® Advance® Infant formula, both of which are available from Ross Products Division, Abbott Laboratories, Columbus, Ohio, USA.
These polyunsaturated fatty acids, however, tend to be more sensitive to oxidation than many other ingredients commonly found in nutritional formulas. Due to their chemical structure, exposure to heat and atmospheric levels of oxygen can cause a series of chemical reactions about their carbon:carbon double bonds resulting in free radical formation. These free radicals can continue to break down the polyunsaturated fatty acids in an auto-oxidative process. The result is the development of undesirable off-flavors and odors and the eventual degradation of the beneficial polyunsaturated fatty acids. These polyunsaturated fatty acids are especially susceptible to oxidation during high-heat processing, spray drying processing, or even during relatively short storage periods after the formula has been sealed and packaged. Oxidative stability has become especially challenging with recent infant formulas that contain relatively high concentrations of arachidonic and decosahexaenoic acid for optimal eye and cognitive development.
One method of controlling the undesirable oxidation of polyunsaturated fatty acids in nutritional formulas, especially in powder formulas, is the addition of antioxidants such as those described in U.S. Pat. No. 5,234,702 (Katz et al.) including ascorbyl palmitate, beta-carotene, mixed tocopherols, and others. Beta-carotene has been found particularly useful as an antioxidant in the oil blends described by Katz et al., and includes antioxidant systems in which beta-carotene is used at concentrations ranging from 6–12 ppm by weight of the total oil content of the infant formula.
As an antioxidant, however, beta-carotene tends to discolor the otherwise white-appearing nutritional formula, especially infant formulas, with a red-orange carotenoid hue. These colors can stain clothing and are often viewed as a negative by many consumers. Although off colors can be eliminated by simply removing the beta-carotene from the formula, such removal is not generally desirable from a nutrition standpoint, and will also generally result in an unacceptable reduction in oxidation stability within the formula, with the subsequent development of rancid odors especially in those powder formulations containing ARA and DHA.
It has now been found, however, that nutritional formulas containing polyunsaturated fatty acids can be formulated with beta-carotene for optimal antioxidant performance without imparting to the finished product a carotenoid-like red-orange hue. This has been accomplished by preparing a nutritional formula with carbohydrate, protein, lipid, and from 0.25 ppm to 10 ppm of a carotenoid-containing antioxidant combination by weight of the total oil component of the formula, wherein the carotenoid combination comprises beta-carotene, lutein, and lycopene, at preferred weight ratios of (i) lutein to beta-carotene of from about 0.01966:1 to about 59:1, (ii) lycopene to beta-carotene of from about 0.00805:1 to about 114:1, and (iii) lutein to lycopene of from about 0.0117:1 to about 108:1.
The data as set forth herein shows selected carotenoid combinations can provide the same or better antioxidant performance as antioxidant systems containing up to six times as much beta-carotene as total carotenoid in the infant formulations of the present invention. Moreover, it has also been shown from the data that this particular combination of carotenoids also greatly reduces the red-orange carotenoid hue in the finished formula, without a corresponding reduction in antioxidant activity.
It is therefore an object of the present invention to provide nutritional formulas, especially infant formulas, containing a polyunsaturated fatty acid with an effective antioxidant system, and further to provide such a system that contains a carotenoid-containing antioxidant. It is a further object of the present invention to provide such a formula, wherein the formula has improved color, with little or no red-orange carotenoid hue. It is yet another object of the present invention to provide such a formula containing relatively high concentrations of polyunsaturated fatty acids, especially a combination including arachidonic, eicosapentaenoic, and/or decosahexaenoic acids. It is a further object of the present invention to provide such benefits in a powder nutritional formula.